The present invention relates to an oxygen absorbent.
An oxygen absorbent is broadly used as sealed into a food pack for the purpose of preventing the food from deteriorating due to denaturation, discoloration, oxidation and the like. Typical oxygen absorbents which have been widely used include an oxygen absorbent comprising an iron powder and an oxygen absorbent comprising an ascorbic acid. The oxygen absorbent according to the present invention belongs to the latter.
In a general form the oxygen absorbent comprising the ascorbic acid is used packed into an air permeable small bag together with another additives. Various improved methods have been proposed in this type oxygen absorbent, for instance, (1) improvement in the oxygen absorbability of ascorbic acid by the addition of an alkaline material or a deliquescing material (e.g. Japanese Patent Application KOKAI Nos. 54-132246, 55-61914, and 54-98348), and (2) allowing an aqueous solution of the above composition (1) to adsorb into an suitable adsorbent and to granulate the resultant, if necessary (e.g. Japanese Patent Application KOKAI Nos. 47-30845, 53-46490, 54-8186). The method (1) aforementioned is worse in the productivity because of the deliquescence due to the alkaline material or deliquescing material, which makes the packing efficiency worse and the high speed packing impossible. The method (2) aforementioned can improve the above defect of the method (1), but in KOKAI No. 53-46490 too much amount of absorbent is required to adsorb an sufficient amount of water and ascorbic acid in the adsorbent as exemplified pulp, soybean protein, popcorn powder, polyurethane, sawdust, diatomaceous earth, and the like. In KOKAI No. 54-8186 the alkaline material is used adsorbed in a diatomaceous earth. The both methods are insufficient in the flowability of the powder.
The Japanese Patent Application KOKAI No. 59-232078 discloses a granular oxygen absorbent in which an activated carbon is used as a binder. In this method complicate operation and a high price machine are indispensable for the granulating process.
The Japanese patent Application KOKAI No. 59-29033 proposes the use of carbon black as a filler to improve the flowability in the automatic packaging process and to pack it with correct measurement. This publication also discloses the co-use of ascorbic acid and an iron compound.
The use of carbon black, however, makes the appearance diety because the black powder adheres at the sealing portion of the small bag at packing, or pollutes the working condition by the black dust. As the appearance of the pack is liable to become blackish and deteriorate the commercial value for foods, especially, the packing operation must be strictly controlled. Further, as the powder easily coagulates and is worse in flowability, the granulation is in dispensable. In addition, a carbon black is dangerous because of possible firing when supplied in a microwave oven together with the packaged food.